Multiple disc clutch assemblies for coupling to and decoupling from a source of torque are well-known in the art. For example, see U.S. Pat. Nos. 1,886,865, 3,291,272 and 3,317,013.
However, such prior art clutches have disadvantages. For one, the prior art clutches are typically mechanically complex with complicated linkage mechanisms for achieving clutch engagement and disengagement. Also, the prior art clutches usually require confined housing or other surrounding support structure that restricts airflow around the various components of the clutch, thereby limiting clutch life and decreasing efficiency by providing insufficient cooling and permitting heat buildup.
U.S. Pat. No. 4,977,991 ("the '991 patent"), which is assigned to the assignee of the present invention, provides a multiple disc clutch assembly 10 which achieves clutch engagement and disengagement in a more efficient and effective manner than the prior art clutches discussed above. The '991 patent accomplishes this by including activating dowels 50 slidably mounted in apertures 52 in a resilient plate 36 of the clutch assembly 10 to engage and disengage the clutch 10 (col. 4, lines 1-22).
Although the clutch assembly 10 of the '991 patent provides a significant improvement over other clutch assemblies, the clutch assembly 10 of the '991 patent has disadvantages worth noting. First, the activating dowels 50 tend to wear out faster than is desired. Thus, the clutch assembly 10 is costlier to maintain than is desired. And second, there is undesirable rattling or knocking of discs and the activating dowels 50 in the clutch assembly design of the '991 patent.
What is desired, therefore, is a disc clutch assembly which achieves clutch engagement and disengagement in an effective and efficient manner without use of complicated linkage mechanisms, which provides sufficient airflow to prevent damaging heat buildup, which reduces undesirable rattling or knocking of discs, and which decreases the wear of clutch assembly components.